engleski

Relevance of biotic parameters in assessment of the spatial distribution of gastrointestinal metal and protein levels during spawning period of European chub (Squalius cephalus L.)

The present field study, conducted during the spawning period (April/May) of European chub (Squalius cephalus L.) from the Sava River in Croatia, indicates that seasonal changes of fish physiological state might cause variability in gastrointestinal metal (Cd, Cu, Fe, Mn, Zn), total cytosolic protein and metallothionein (MT) levels. During the period of fish spawning and increased metabolic activity, significant relationship with chub hepatosomatic index was evident for Fe and Mn in gastrointestinal tissue (r=0.35 and 0.26, respectively) and in cytosolic fraction (r=0.32 and 0.41, respectively) and for Zn and Fe in the gut content (r=0.36 and 0.31, respectively). Total cytosolic protein and MT concentrations followed the same spatial distribution as Fe and Mn in all gastrointestinal fractions and as Zn in the sub- cellular fractions, with higher levels at upstream locations. Due to their role in metabolic processes and gonad development, influence of increased feeding and spawning activity in April/May was reflected on gastrointestinal essential metals (Fe, Mn and Zn) and MT concentrations, which probably follow increase in Zn concentrations, known as the primary MT inducer. Therefore, biotic factors should be considered as important confounding factors in metal exposure assessment, while their influence on gastrointestinal metal and protein levels should be interpreted depending on the season studied.

hepatosomatic index; gut content; essential metals; Cd; metallothionein; total cytosolic proteins

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